Speciation of Oxygen Functional Groups on the Carbon Support Controls the Electrocatalytic Activity of Cobalt Oxide Nanoparticles in the Oxygen Evolution Reaction

Abstract

The effective use of the active phase is the main goal of the optimization of supported catalysts. However, carbon supports do not interact strongly with metal oxides, thus, oxidative treatment is often used to enhance the number of anchoring sites for deposited particles. In this study, we set out to investigate whether the oxidation pretreatment of mesoporous carbon allows the depositing of a higher loading and a more dispersed cobalt active phase. We used graphitic ordered mesoporous carbon obtained by a hard-template method as active phase support. To obtain different surface concentrations and speciation of oxygen functional groups, we used a low-temperature oxygen plasma. The main methods used to characterize the studied materials were X-ray photoelectron spectroscopy, transmission electron microscopy, and electrocatalytic tests in the oxygen evolution reaction. We have found that the oxidative pretreatment of mesoporous carbon influences the speciation of the deposited cobalt oxide phase. Moreover, the activity of the electrocatalysts in oxygen evolution is positively correlated with the relative content of the COO-type groups and negatively correlated with the CO-type groups on the carbon support. Furthermore, the high relative content of COO-type groups on the carbon support is correlated with the presence of well-dispersed Co3O4 nanoparticles. The results obtained indicate that to achieve a better dispersed and thus more catalytically active material, it is more important to control the speciation of the oxygen functional groups rather than to maximize their total concentration.

Insights on MOF-derived metal–carbon nanostructures for oxygen evolution

“…[30][31][32] For instance, Goscianska et al correlated the relationship between the morphology of synthesized MOFderived cobalt-containing carbons and their activity and stability in OER. 33 Additionally, Zheng et al impregnated Ni-MOF precursor with ferrocene and utilized the subsequently derived carbon for efficient oxygen oxidation. 34 Besides, our group modified the unique NiOF-1 nanorod with Fe 3+ and the derivatives exhibited excellent OER property.…”

Heterostructure of Fe-Doped CoMoOx/CoMoOx as an Efficient Electrocatalyst for Oxygen Evolution Reaction

“…18 To address these challenges, carbon supports and metal oxides−carbon composites have been explored to improve carrier transport. 21,22 Nevertheless, the introduction of carbon supports requires additional processes, and transition-metal oxide catalysts on carbon supports are susceptible to detachment during the OER due to weak physisorption or van der Waals interactions, leading to shortterm catalytic activity. Instead of carbon supports, introducing oxygen vacancy (O v ) in metal oxide-based catalysts enhances OER catalytic performance by increasing the electrical conductivity of metal oxides themselves, 11,23 and optimizing the mismatched binding energies of oxygen-containing species (based on widely accepted OER activity descriptor of ΔG O − ΔG OH ) through the presence of excess electrons in metal oxides.…”

“…However, these amorphous mixed-metal oxides and hydroxides often exhibit low stability and low intrinsic conductivity, which can limit their catalytic performance during OER, particularly at high current densities . To address these challenges, carbon supports and metal oxides–carbon composites have been explored to improve carrier transport. , Nevertheless, the introduction of carbon supports requires additional processes, and transition-metal oxide catalysts on carbon supports are susceptible to detachment during the OER due to weak physisorption or van der Waals interactions, leading to short-term catalytic activity.…”

Co3O4 Supported on Graphene-like Carbon by One-Step Calcination of Cobalt Phthalocyanine for Efficient Oxygen Reduction Reaction under Alkaline Medium

“…The presence of mixed valences of Co cations in the crystal structure could provide donor–acceptor chemisorption sites for the reversible adsorption of oxygen, thus favouring the ORR process [ 10 , 26 , 27 ]. Moreover, integrating the carbon-based materials with Co 3 O 4 can further improve the relatively high electrocatalytic activity and enhance the durability generated by a synergistic effect between the two components [ 28 , 29 , 30 , 31 , 32 , 33 ]. However, there are only several works which report on the combination of Co 3 O 4 and carbon-based materials via a one-step synthesis method for ORR.…”